authz: add QAuthZSimple object type for easy whitelist auth checks

In many cases a single VM will just need to whitelist a single identity
as the allowed user of network services. This is especially the case for
TLS live migration (optionally with NBD storage) where we just need to
whitelist the x509 certificate distinguished name of the source QEMU
host.

Via QMP this can be configured with:

  {
    "execute": "object-add",
    "arguments": {
      "qom-type": "authz-simple",
      "id": "authz0",
      "props": {
        "identity": "fred"
      }
    }
  }

Or via the command line

  -object authz-simple,id=authz0,identity=fred

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 119 insertions, 0 deletions

diff --git a/authz/Makefile.objs b/authz/Makefile.objs
index 12597c9..2a75d53 100644
--- a/authz/Makefile.objs
+++ b/authz/Makefile.objs
@@ -1 +1,2 @@
 authz-obj-y += base.o
+authz-obj-y += simple.o
diff --git a/authz/simple.c b/authz/simple.c
new file mode 100644
index 0000000..8ab7188
--- /dev/null
+++ b/authz/simple.c
@@ -0,0 +1,115 @@
+/*
+ * QEMU simple authorization driver
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "authz/simple.h"
+#include "authz/trace.h"
+#include "qom/object_interfaces.h"
+
+static bool qauthz_simple_is_allowed(QAuthZ *authz,
+                                     const char *identity,
+                                     Error **errp)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(authz);
+
+    trace_qauthz_simple_is_allowed(authz, sauthz->identity, identity);
+    return g_str_equal(identity, sauthz->identity);
+}
+
+static void
+qauthz_simple_prop_set_identity(Object *obj,
+                                const char *value,
+                                Error **errp G_GNUC_UNUSED)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    g_free(sauthz->identity);
+    sauthz->identity = g_strdup(value);
+}
+
+
+static char *
+qauthz_simple_prop_get_identity(Object *obj,
+                                Error **errp G_GNUC_UNUSED)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    return g_strdup(sauthz->identity);
+}
+
+
+static void
+qauthz_simple_finalize(Object *obj)
+{
+    QAuthZSimple *sauthz = QAUTHZ_SIMPLE(obj);
+
+    g_free(sauthz->identity);
+}
+
+
+static void
+qauthz_simple_class_init(ObjectClass *oc, void *data)
+{
+    QAuthZClass *authz = QAUTHZ_CLASS(oc);
+
+    authz->is_allowed = qauthz_simple_is_allowed;
+
+    object_class_property_add_str(oc, "identity",
+                                  qauthz_simple_prop_get_identity,
+                                  qauthz_simple_prop_set_identity,
+                                  NULL);
+}
+
+
+QAuthZSimple *qauthz_simple_new(const char *id,
+                                const char *identity,
+                                Error **errp)
+{
+    return QAUTHZ_SIMPLE(
+        object_new_with_props(TYPE_QAUTHZ_SIMPLE,
+                              object_get_objects_root(),
+                              id, errp,
+                              "identity", identity,
+                              NULL));
+}
+
+
+static const TypeInfo qauthz_simple_info = {
+    .parent = TYPE_QAUTHZ,
+    .name = TYPE_QAUTHZ_SIMPLE,
+    .instance_size = sizeof(QAuthZSimple),
+    .instance_finalize = qauthz_simple_finalize,
+    .class_size = sizeof(QAuthZSimpleClass),
+    .class_init = qauthz_simple_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+
+static void
+qauthz_simple_register_types(void)
+{
+    type_register_static(&qauthz_simple_info);
+}
+
+
+type_init(qauthz_simple_register_types);
diff --git a/authz/trace-events b/authz/trace-events
index 481c90f..1ef796c 100644
--- a/authz/trace-events
+++ b/authz/trace-events
@@ -2,3 +2,6 @@
 
 # authz/base.c
 qauthz_is_allowed(void *authz, const char *identity, bool allowed) "AuthZ %p check identity=%s allowed=%d"
+
+# auth/simple.c
+qauthz_simple_is_allowed(void *authz, const char *wantidentity, const char *gotidentity) "AuthZ simple %p check want identity=%s got identity=%s"